Electronic musical instrument

ABSTRACT

An electronic musical instrument includes a tunable master oscillator and digital frequency dividers for synthesizing musical notes and their harmonics to provide a multi-voice instrument having celeste and vibrato features. Automatic accompaniment with tone and percussive sounds is provided. A tempo clock and a beat counter sequentially operate a series of gates to pass signals from the harmonic generating divider to trigger percussive sound generators. The key in which the accompaniment is played is selectable by the keyboard, and is determined by the frequency of the signal applied to a harmonic generating divider. The melody pattern played is determined by an accompaniment program which may be either internally or externally programmed.

United States Patent 1 Maynard ELECTRONIC MUSICAL INSTRUMENT [75] Inventor: Fred B. Maynard, Phoenix, Ariz.

[73] Assignee: Motorola, Inc., Franklin Park, Ill.

[22] Filed: Sept. 30, 1971 [21] Appl. No.1 185,012

[52] U.S. Cl. ..84/1.24, 84/l.1 l, 84/l.12,

84/1.19, 84/1.21, 84/D1G. 4 [51] Int. Cl. G10h 1/02 [58] Field of Search 84/10], 1.03, 1.17,

84/124, 1.25, 1.26, DIG. 4, DIG. 11, 1.23, 1.2, 1.19, 1.11, 1.22, DIG. 8

OTHER PUBLICATIONS Richard Phillips, Many Digital Functions can Be Oct. 9, 1973 Generated," Electronic Design, February 1, 1968, pages 82-85.

Primary Examiner-Richard B. Wilkinson Assistant Examiner-U. Weldon Attorney-Vincent J. Rauner et a1.

[57] ABSTRACT An electronic musical instrument includes a tunable master oscillator and digital frequency dividers for synthesizing musical notes and their harmonics to provide a multi-voice instrument having celeste and vibrato features. Automatic accompaniment with tone and percussive sounds is provided. A tempo clock and a beat counter sequentially operate a series of gates to pass signals from the harmonic generating divider to trigger percussive sound generators. The key in which the accompaniment is played is selectable by the keyboard, and is determined by the frequency of the signal applied to a harmonic generating divider. The melody pattern played is determined by an accompaniment program which may be either internally or externally programmed.

22 Claims, 3 Drawing Figures United States Pa tent Maynard 5] Oct. 9, 1973 VIBRATO OSCILLATOR DIVIDER HAVING J2 'Q E E RELATIONSHIP BETWEEN/ I2 OUTPUT FREQUENCIES ocTAvE DIVIDER T ORGAN ToNE GENERATING I l DIVIDERS 20w ACCOMPANIMENT KEY SWITCHES i SOLO KEY SW'TCHES ORGAN 4 40 I KEY SWITCHES f 52 44 LEADS ORGAN FILTERS 55 HARMONIC GENERATING DIVIDER I 4/ 43 45 I IIIII I 6, I HARMONIC I I v AMPLITUDE I J ACCOMPANIMENT CONTROL TONE DIVIDER 44 F r HARMONIC ILTER 4.9

FILTERS 48 TONE GATE ACCOMPANIMENT PROGRAM I I r I I I I I 36 PERCUSSION I: PERCUSSION I COUNTER GENERATORS PROGRAM TEMPO I OUTPUT AMPLIFIER SHEET 10F 3 VIBRATO OSCILLATOR DIVIDER HAVING J2- RELATIONSHIP BETWEEN,

OUTPUT FREQUENCIES MASTER OSCILLATOR ORGAN TONE GENERATING DIVIDERS 44 LEADS! ORGAN KEY SWITCHES 44LEADS ORGAN FILTERS OCTAVE DIVIDER v ACCOMPANIMENT KEY SWITCHES SOLO KEY SWITCHES HARMONIC GENERATING DIVIDER HARMONIC AMPLITUDE CONTROL III HARMON IC FI LTERS ACCOMPANIM ENT TONE DIVI D ER CELESTE FILTER ACCOMPANIMENT PROGRAM IIIIIII TONE GATE PERCUSSION GENERATORS PERCUSSION PROGRAM COUNTER TEMPO J CLOCK r OUTPUT TO AMPLIFIER PATENTED BET SHEET 2 8F 3 DECADE COUNTER TEM P0 CLOCK 39 ACCOMPAN IMENT OUTPUT TO AMPLIFIERS PATENTED elm 3'. 764.721

SHEET 30F 3 7 42 46 FROM 501.0 I --7 KEY SWITCHES 4o| HARMONIC OUTPUT TO AMPLIFIERS 1 ELECTRONIC MUSICAL INSTRUMENT BACKGROUND This invention relates generally to electronic musical instruments, and more particularly to electronic keyboard instruments having variable voice, celeste and automatic accompaniment features.

There are many musical instruments wherein it is desirable to provide automatic accompaniment and a multiplicity of voices and sound effects. One such musical instrument is the electronic organ. Although several techniques for providing automatic accompaniment and special effects are known, presently known systems generally employ gating circuits that selectively pass signals from separate percussive sound and musical chord generators. Special effects are generally achieved through the use of multiple oscillators and wave shaping filters.

Whereas these techniques provide ways to achieve automatic accompaniment and other special effects, the accompaniment is limited to a relatively small number of simple patterns that can be played using a limited number of sounds, and the special effects are limited by the relatively few frequencies that can be generated when wave shaping circuits and multiple oscillators are used.

SUMMARY It is an object of the present invention to provide an improved electronic musical instrument having automatic accompaniment with a multiplicity of voices and special effects.

It is a further object of this invention to provide an automatic accompaniment system having a large number of accompaniment patterns.

It is another object of this invention to provide a musical instrument having an accompaniment system that plays a wide variety of musical tones.

Still another object of this invention is to provide a musical instrument having an automatic accompaniment system having melody patterns that can be programmed by means internal to the instrument or externally through the use of plug-in cards or switches to give a wide variety of musical patterns.

A still further object of this invention is to provide a musical instrument having an automatic accompaniment system that provides tone accompaniment in a variety of selectable keys upon actuation of one of a series of single contact switches.

Still another object of this invention is to provide a musical instrument capable of special effects such as celeste.

Yet another object of this invention is to provide a musical instrument having variable voices which are synthesized by mixing a fundamental tone and a series of harmonics each having an individually controllable amplitude.

In accordance with the invention, a tone generating system is employed having a master oscillator from which all necessary tones are synthesized through the use of a digital divider. The digital divider has a multiplicity of divisor numbers, and provides output signals having a frequency relationship approximately equal to the twelfth root of two for synthesizing the equal tempered musical scale. In addition, the divider provides output signals that are harmonically related to the tones of the equal tempered musical scale. These harmonics may be combined in any desired proportion with a fundamental tone to provide various voices. Celeste may be achieved by generating several closely spaced tones using parallel dividers with slightly different divisor numbers and combining the resultant tones.

An automatic accompaniment system including a tempo clock and a series of gates selectively sounds the tones from a harmonic generator and from a percussive sound generator in a predetermined pattern to achieve melodious accompaniment. The key in which the automatic accompaniment is played is selected by a single contact switch which controls the frequency of the signal applied from the octave divider to the harmonic generator. This switch may be part of the regular organ keyboard or may be part of a bank of accompaniment switches.

This system is applicable to all keyboard type electronic musical instruments, particularly an organ. When combined, the features of the present invention provide a musical instrument having great versatility.

DESCRIPTION OF THE DRAWINGS In the drawings:

FIG. 1 is a block diagram of an electronic organ according to the invention;

FIG. 2 is a block diagram of the automatic accompaniment portion of the organ; and

FIG. 3 is a combined block and schematic diagram of the harmonic generation system of the organ.

DETAILED DESCRIPTION Referring now to the drawings in greater detail, FIG. I shows in block diagram form one embodiment of the invention used in an electronic organ. All tones produced by the organ, except percussive sounds, are generated by digital divider chains using master oscillator 10 as a reference. The digital dividers used in these chains are well known in the art, particularly in the field of computers. The frequency of master oscillator 10 may be changed by adjusting frequency control 12. In this way, the key to which the instrument is tuned may be changed using a single control. Vibrato oscillator 14 is a low frequency oscillator operating at approximately 6 cycles per second, and is coupled to master oscillator 10 to vary the frequency of master oscillator 10 at the six cycle rate to provide a vibrato effect. The depth of the vibrato is varied by changing the amplitude of the 6 cycle per second signal from vibrato oscillator 14.

Master oscillator 10 is coupled to tone generating divider l6,which provides 12 output signals having frequencies which are sub-multiples of the frequency of the output signal from master oscillator 10. Divider 16 includes twelve divider chains, each chain having a divisor number that is related to the divisor numbers of the other dividers by the twelfth root of two. As a result, the frequencies of the 12 output signals from divider 16 have frequencies that are related to each other by the twelfth root'of two. It is possible to synthesize a complete equal tempered musical scale, which also has a twelfth root of two frequency relationship between tones, from the 12 output signals from divider 16. Also, since the divisor numbers of the divider chains cannot change with the time, the twelfth root of two frequency relationship is maintained and the instrument cannot go out of tune.

The 12 output signals from divider 16 are routed to accompaniment key switches 20, octave divider l7 and organ tone generating dividers 18 for further processing to provide automatic accompaniment, special effects and organ tones.

The 12 outputs from divider 16 are connected to a bank of 12 accompaniment key switches 20. Accompaniment key switches 20 allow one of the signals from divider 16 to pass to the automatic accompaniment circuitry. A single keyswitch is depressed to determine the key in which the accompaniment will be played. The key switches are wired such that in the event that two or more keys are pressed simultaneously, only the highest frequency signal will pass. Accompaniment key switches 20 are connected to a divider chain comprising divide by two dividers 21, 22 and 23, and selector switch 24. Selector switch 24 extends the range of the automatic accompaniment system to four octaves. Oc-

tave selection is made by positioning selector switch 24 to pass a signal either from accompaniment key switches 20 or from one of the dividers 21, 22 or 23.

Accompaniment tone divider 30 is connected to selector switch 24 to receive a signal whose frequency is determined by the frequency of the tone selected by octave selector switch 24 and by depressing one of the key switches 20. The signal from selector switch 24 is frequency divided by the accompaniment tone divider 30 to provide a fundamental tone. In addition, other harmonically related tones are simultaneously producedby accompaniment tone divider 30 through the use of lower divisor numbers than were used to produce the fundamental tone. In this particular embodiment, the accompaniment tone divider 30 simultaneously produces nine harmonically related output tones. The operation of the accompaniment tone divider 30 will be discussed more fully elsewhere in this specification.

Accompaniment tone divider 30 is coupled to tone gate 32. Tone gate 32 sequentially passes tones from the accompaniment tone divider 30 in accordance with control signals applied to the gates from the accompaniment program 34. The control signals from the accompaniment program 34 are controlled by tempo clock 38 which isconnected to and provides tempo pulses to counter 36 at the beat rate. The repetition rate of the beat pulses from clock 38 is controlled bycontrol 39, and is adjustable from about 40 to 500 beats per minute. Counter 36 has eight outputs and sequentially provides output pulses at each of its outputs to produce an eight-beat sequence. This is suitable for accompaniment to music in 4/4, 8/8 and similar times. Alternately, the counter can provide a six pulse sequence suitable for 3/4 and 6/8 time. The eight outputs from counter 36 are connected to accompaniment program 34.

Accompaniment program 34 is also connected to tone gate 32. In one embodiment, accompaniment program 34 includes a series of jumper wires which connect the outputs of counter 36 to gate 32 in a predetermined fashion so that, for example, a first note is sounded on the first beat, another note on the second beat, etc. In another embodiment, accompaniment program 34 comprises a series of switches which selectively couple the outputs from counter 36 to tone gate 32 in a predetermined fashion. Alternately, accompaniment program 34 can include plug-in cards which are prewired to make the desired connections.

Percussion program 33 is also connected to counter 36 and controls percussion generators 31. Percussion program 33 is similar to accompaniment program 34, and causes percussion generators 31 to sound in a predetermined sequence in response to output pulses from counter 36. Percussion program 33 and accompaniment program 34 may be separate programs as shown in FIG. 1, or may be combined into a single program. Percussion generators 31 may include several ringing circuits to simulate the sounds of drums, wood blocks, brushes, cymbals, and other percussive instruments. The percussive sounds may be sounded simultaneously with the tone signals or may be alternated therewith. The outputs from percussion generators 31 and from tone gate 32 are combined and are applied to amplifiers and audio reproduction circuits. The automatic accompaniment is played by selecting the desired accompaniment program, as by use of switches or cards, selecting the desired octave by means of switch 24, and depressing one of the accompaniment key switches 20 to initiate play. The pitch of the accompaniment melody is readily changed by depressing different key switches.

The 12 outputs from tone generating divider 16 are also connected to special effects circuits including octave divider 17. Octave divider 17 includes several divide by two circuits to synthesize a series of signals having the twelfth root of two frequency relationship of the signals from tone generating divider l6 and displaced by one or more octaves from the signals of divider 16. In the present embodiment, octave divider 17 has 30 output signals, giving a total range of 2 /2 octaves. A bank of solo key switches 40 is coupled to octave divider 17 to select one of the thirty signals from octave divider l7 and apply the same to the harmonic generating divider 42 and to celeste generating divider 44. The bank of solo key switches 40 is wired to allow only the highest frequency signal to pass should more than one of the key switches be simultaneously depressed. Switches 51 and 52 are for selectively disabling the special effect circuits.

The harmonic generating divider 42 includes divider chains similar to those used in the accompaniment tone divider 30 to produce a fundamental tone and nine harmonically related tones. A more detailed description of the harmonic generator is given elsewhere in the specification.

The ten outputs from harmonic generator 42 are connected to a bank of ten harmonic amplitude controls 46 to allow the amplitude of each harmonic to be individually controlled. The amplitude controls are available at the console of the instrument to allow the performer to readily adjust harmonic amplitudes to produce a wide variety of voices. A series of harmonic filters 48 is coupled to the harmonic amplitude controls 46. The ten harmonic signals from the harmonic amplitude controls 46 are filtered by the harmonic filters 48 to provide the desired tones and are combined to form a single composite signal which is applied to the amplifiers and audio reproduction circuitry.

The output signal from the solo key switches 40 is also applied to celeste generating divider 44 which includes a series of parallel connected divider chains 41, 43 and 45 having slightly different divisor numbers, in this case 59, and 61, respectively. The difference between the divisor numbers should be on the order of between 0 to approximately 3 percent, generally approximately 2 percent. The output signals from the three celeste dividers 41, 43 and 45 have slight frequency offsets therebetween, and produce a complex waveform when the outputs of the three dividers are combined in celeste filter 49 at the output of celeste generator 44. Celeste filter 49 has a low pass characteristic and a bypass switch to produce either a deep tone when the filter is in, or a bright tone when the filter is bypassed. Both tones sound like the tone produced by several organs sounded simultaneously when reproduced by the audio amplifying and reproduction circuitry.

The twelve output signals from the tone generating divider 16 are also applied to a series of organ tone generating dividers 18 which include a series of divide by two dividers for synthesizing other series of frequencies having a twelfth root of two relation therebetween, and being displaced by one or more octaves from the signals from tone generating divider 16. In this embodiment, the bank of organ tone generating dividers 18 provides 44 output signals having an equal tempered scale relationship. A bank of organ key switches 50 is coupled to the organ tone generating dividers l8 and receives the 44 frequency related signals from the generating dividers. The bank of organ key switches 50 selectively passes one or more of the signals from dividers 18 to the organ filters 55. The bank of organ filters 55 includes a plurality of wave shaping filters which operate on the 44 tones to provide various organ sounds. The outputs from the organ filters 55 are combined to provide a composite signal for the amplifiers and audio reproduction circuitry.

In one embodiment of the organ, a single keyboard comprising 44 keys is used. Each key has two sets of switch contacts that are activated when the key is depressed. One set of contacts acts as an organ key switch 50 for producing an organ tone. The second set of contacts on each of the 30 highest frequency organ keys is used as a solo key switch 40. This allows either organ or special effects or a combination of both to be played on the 30 high frequency keys of the keyboard. The second set of contacts on each of the twelve lowest frequency keys is used as an accompaniment key switch 20. This allows either organ tones or automatic accompaniment to be played on the 12 low frequency keys. Simultaneous low frequency organ and automatic accompaniment is not generally desired, and has not been provided.

Referring now to FIG. 2, the automatic accompaniment circuitry is shown in greater detail in this circuit. The accompaniment tone divider 30 is coupled to selector switch 24 and receives an alternating current signal therefrom. The frequency of the alternating signal applied to divider 30 depends upon the position of selector switch 24, and upon the frequency of signal selected by the accompaniment key switches 20 of FIG. 1. Accompaniment tone divider 30 includes several digital frequency dividers having various divisor numbers such as, for example, 2, 3, 4, 5, 8, 17 and 19. The block 30 in FIG. 2 shows how these dividers are connected to each other in a combination series-parallel configuration to provide nine predetermined divisor numbers. The divisor numbers resulting from the configuration of the embodiment shown are indicated at the nine points'of interconnection between divider 30 and tone gate 32.

.Tone gate 32 includes nine two-input AND gates 60 through 68 of standard design and nine summing resistors, 70 through 78. Gates 60 through 68 are normally in an inhibit or non-conducting state. The gates are rendered conductive by the presence of a control signal pulse applied thereto. Removal of the control signal allows the gate to return to its non-conducting state.

Tempo clock 38 produces output pulses at a rate determined by the tempo of the music to be played. The frequency of output signals from the tempo clock can be varied by adjusting control 39. Tempo clock 38 is connected to counter 36 which includes a standard decade counter 80, and binary to decimal converter 85. The output pulses from tempo clock 38 are counted by decade counter which produces the count in binary form at output points 81 through 84. The binary to decimal converter is coupled to decade counter 80 and receives the binary information representing the tempo count from the output points 81 through 84 of the decade counter. The information appearing at output points 81 through 84 is converted to decimal form and appears at output points through 109. The count is represented by an output pulse appearing first at output 100, and moving sequentially from point 100 to point 101 and then to point 102, etc., in synchronism with the pulses from tempo clock 38.

A feedback loop including a two position tempo selector switch 86 is provided between the binary to decimal converter 85 and the decade counter 80. The feedback loop resets decade counter 80 when a predetermined count is reached by the binary to decimal con verter 85. For example, when switch 86 is in the 4/4 position, pulses will sequentially pass from output 100 to output 108 of the binary to decimal coverter 85. When the output pulse reaches output 108, decade counter 80 will be reset to zero causing the output pulse from the binary to decimal converter 85 to immediately switch from point 108 to point 100. This provides a repetitive eight count sequence suitable for accompaniment in 2/4, 4/4 and related time. Placing selector switch 86 in the 3/4 position causes decade counter 80 to reset when the output pulse from binary to decimal converter 85 reaches output 106. This provides a six count sequence suitable for accompaniment in 3/4 time. Output 109 is present on standard binary to decimal converters and is not used in this embodiment, however, a converter having more than 8 outputs can be used to provide a more complex musical sequence.

Accompaniment program 34 is used to interconnect counter 36 and gates 60 through 68 in a predetermined manner. Although jumper wires are shown in the circuit of FIG. 2, switches or program cards can also be used. FIG. 2 shows a simple pattern wired into program 34. In this program, output 100 is connected to gate 64, outputs 101 and 102 are connected to gate 63, output 104 is connected to gates 65 and 66 and output 105 is connected to gate 67. In operation, gate 64 is opened on the first beat when a pulse is present at output 100. This allows a signal having a frequency equal to the frequency of the signal applied to divider 30, and divided by 24 in the divider 30, to pass through gate 64 and resistor 74 to output bus 79. Gate 63 is opened on the second and third beats when pulses are present at output 101 and 102, and this allows a higher frequency tone to pass through gate 63 and resistor 73 to output bus 79. The frequency of the tone passed during the second and third beats is equal to the frequency of the signal applied to divider 30, divided by 18. Since output 103 is not connected to 'a gate, no tone is passed during the fourth beat when the output pulse appearsat output 103. During the fifth beat, when the output pulse appears at output 104, gates 65 and 66 are opened simultaneously allowing two tones to be passed to output bus 79. Similarly, gate 67 is opened during the sixth beat, and the sequence is repeated after either six or eight beats, depending on the position of switch 86.

Program 34 is very flexible allowing any number of gates to be opened on any beat. Program 33, which is similar to and may be part of program 34, is used to control percussion generators 31 of FIG. 1. This can operate in the manner described above for program 34, to provide a wide variety of musical patterns which may have simultaneous tone and percussive sounds.

FIG. 3 shows harmonic generating divider 42, harmonic amplitude control 46 and harmonic filters 48 of the system of FIG. 1 in a combined block and schematic diagram. Harmonic generating divider 42 is connected to the bank of solo key switches 40 of FIG. 1, and receives one of the 30 output signals from octave divider 17. I-larmonic generating divider 42 comprises a series-parallel connection of frequency dividers, similar to that of accompaniment tone divider 30. The dividers used in harmonic generating divider 42 have relatively low division ratios such as, for example, 2, 3 and 5. Harmonic generating divider 42 has ten outputs which are connected to the potentiometers 110 through 119 of harmonic amplitude control 46. The ten output signals from harmonic generating divider 42 have frequencies that are harmonically related to each other by a ratio of small whole numbers. This ratio is determined by the number of frequency divisions that a particular output signal has undergone relative to the other output signals.

When considering the outputs from divider 42, no single output signal should be considered the fundamental with the others being harmonics of that fundamental, but rather, the ten outputs should be considered a harmonic system wherein any output may be considered the fundamental and harmonics of that fundamental may be chosen. For example, the frequency of the signal applied to potentiometer 117 may be considered the fundamental frequency, with the frequency of the signal applied to potentiometer 118 being a sec-.

0nd harmonic and the frequency of the signal applied to potentiometer 119 being a fourth harmonic. Alternately, the frequency of the signal applied to potentiometer 118 may be considered the fundamental with the frequency of the signal applied to potentiometer 119 being considered the second harmonic and the frequency of the signal applied to potentiometer 116 being a sixth harmonic. In this manner, a wide variety I of voices may be achieved through the selection of a with, for example, a foot pedal (not shown) to achieve other effects such as, for example, minor thirds.

The 10 outputs from harmonic amplitude control 46 are connected to a series of harmonic filters 48. The bank of harmonic filters 48 includes a series of switches 91, a bank of resistors 93 and a series of low pass filters 95. The bank of switches 91 is connected to the outputs of harmonic amplitude control 46 and to resistor bank 93 and filter the bank 95. Each signal from amplitude control 46 is routed to one of the resistors in resistor bank 93 or to one of the filters of filter bank 95 via one of the switches in switch bank 91. Each switch in switch bank 91 is individually switchable, making it possible to route each harmonic as desired, independently of the setting of the other switches. Resistor bank 93 passes the harmonics from harmonic generating divider 46 unaltered in wave shape to provide a bright effect. Filters 95 are low pass wave shaping filters which provide output signals having a sinusoidal wave shape and provide a flute effect. The outputs of all resistors in resistor bank 93 and all filters in filter bank 95 are connected to output bus 97 wherein all harmonics are combined to provide a composite signal which is applied to the amplifier and reproduction circuitry of the organ.

The embodiment of the invention herein described has been given as a preferred embodiment, but other embodiments using the concepts of this disclosure still fall within the scope of the invention.

In summary, the features of the instant invention provide a very flexible tone and accompaniment system for a musical instrument that is relatively easy to play and tune. The divider type tone generating system accurately maintains the desired musical interval between tones making it unnecessary to tune the organ. In addition, the systhesis of all tones from a single master oscillator makes it relatively easy to provide a vibrato effect by frequency modulating the master oscillator. The automatic accompaniment feature, which provides both tone and percussion accompaniment, allows a novice player to concentrate on playing the melody by freeing him from the accompaniment playing task. The harmonic generating and celeste features allow an expert player to utilize various voices and special effects, and enable him to make a variety of complex and musically interesting renditions.

I claim:

1. An electronic musical instrument having an automatic tone accompaniment system including in combination:

means for providing a plurality of musically related electrical oscillations;

switch means for selecting one of said plurality of oscillations and providing selected oscillations representative thereof connected to said oscillation providing means;

octave selecting means including octave dividing means having a divisor number equal to an integral multiple of two, said octave dividing means having an input connection coupled to said switch means for receiving said selected oscillations and an output connection for providing octavely related oscillations having a frequency related to the frequency of said selected oscillations by an integral multiple of two, said octave selecting means further including octave switch means having first, second and common terminals, said first terminal being coupled to said switch means and said second terminal being coupled to said octave dividing means, said switch means including means for selectively applying one of said selected and octavely related oscillations to said common terminal;

accompaniment frequency dividing means for simultaneously providing a plurality of output signals having frequencies that are related to each other to form a musical scale in response to a signal applied thereto, said accompaniment frequency dividing means having an input junction and an plurality of output junctions, said input junction being connected to said common terminal for receiving the oscillations applied thereto, said accompaniment frequency dividing means including means for providing one of said plurality of output signals to each of said output junctions;

tempo signal means having a plurality of outputs for providing a predetermined sequence of gating signals at each of said outputs; and

gate circuit means having a plurality of input terminals, an output terminal and a plurality of control terminals, each of said input terminals being connected to one of said output junctions of said accompaniment frequency dividing means, said control terminals being connected to said outputs of said tempo signal means, said gate circuit means being responsive to said gating signals for selectively passing said output signals to said output terminal.

2. An electronic musical instrument according to claim 1 wherein said tempo signal means includes variable rate clock means for varying the repetition rate of said gating signals to change the accompaniment tempo.

3. An electronic musical instrument according to claim 1 further including percussion signal generating means connected to said tempo signal means for providing percussion signals in response to said gating signals.

4. An electronic musical instrument according to claim 1 further including means for providing selective interconnections between said tempo signal means and said gate circuit means for varying the sequence of output signals passed to said output terminal connected to said outputs of said tempo signal means and said control terminals of said gate circuit means.

5. An electronic musical instrument according to claim 4 wherein said oscillation providing means includes oscillator means and scale generating frequency dividing means connected to said oscillator means, said frequency dividing means having a plurality of divisor numbers, said divisor numbers having numeric ratios therebetween related by the twelfth root of two.

6. An electronic musical instrument as recited in claim 5 wherein said switch means further includes a plurality of keyswitches connected to said scale generating dividing means for selecting one of said oscillations from said scale generating frequency dividing means upon actuation of one of said keyswitches to thereby select the key in which the accompaniment is played.

7. An electronic musical instrument having a harmonic synthesizing system, said system including in combination:

means for providing a plurality of musically related electrical oscillations;

switch means for selecting one of said plurality of oscillations connected to said oscillation providing means;

harmonic frequency dividing means having an input and a plurality of outputs, said input being connected to said switch means and receiving said selected one of said oscillations therefrom, said harmonic dividing means including means for simultaneously providing a harmonic signal at each of said outputs, wherein each of said harmonic signals has a frequency that is harmonically related to the frequencies of the other harmonic signals and to the frequency of said oscillations;

a plurality of resistive attenuators, each of said resistive attenuators being connected to one of said outputs and receiving one of said harmonically related output signals and selectively attenuating the amplitude thereof; and

combining means connected to each of said resistive attenuators for receiving said harmonic signals therefrom and combining said signals to produce a musical tone having a plurality of individually adjustable harmonics.

8. An electronic musical instrument as recited in claim 7 wherein said frequency dividing means provides variable divisor numbers for varying the frequency relationship between said harmonically related output signals.

9. An electronic musical instrument according to claim 8 wherein said frequency dividing means includes a digital dividing circuit.

10. An electronic musical instrument according to claim 9, said combining means further including a plurality of wave shaping filters, each of said wave shaping filters being connected to one of said resistive attenuators and receiving one of said harmonic signals and providing a wave shape modified harmonic signal.

11. An electronic musical instrument according to claim 10 further including a second plurality of wave shaping filters switchably connected to said plurality of resistive attenuators for selectively providing a second plurality of wave shape modified harmonics.

12. An electronic musical instrument including in combination:

means for generating a plurality of musically related electrical oscillations;

switch means for selecting one of said plurality of oscillations connected to said oscillation generating means;

celeste generating dividing means connected to said switch means, said celeste generating means including a plurality of frequency dividers having slightly different divisor numbers connected to said switch means for receiving said selected one of said plurality of oscillations and providing a plurality of signals having celeste producing frequency offsets therebetween in response to said selected one of said plurality of oscillations; and

means connected to said dividing means for combining said plurality of celeste producing signals.

13. An electronic musical instrument as recited in claim 12 wherein said dividing means includes three parallel connected frequency dividers.

14. An electronic musical instrument as recited in claim 12 wherein said oscillation generating means includes a scale generating divider means for producing a plurality of output signals having frequency relationships therebetween proportional to the twelfth root of two.

15. An electronic musical instrument as recited in claim 14 wherein said switch means includes a plurality of keyswitches for selecting one of said plurality of oscillations, and wherein the divisor numbers are integral numbers that are different from each other by less than approximately three percent.

16. An electronic musical instrument including in combination:

tone generating means including a master oscillator providing a reference signal, frequency dividing means providing divisions in accordance with a plurality of divisor numbers, said dividing means being connected to said master oscillator for receiving said reference signal therefrom and providing output tone signals having a frequency relationship therebetween determined by said divisor numbers, said relationship defining a musical scale;

automatic accompaniment means including tempo clock means providing tempo pulses, counting means connected to said tempo clock means and receiving said tempo pulses therefrom, said counting means having a plurality of outputs sequentially providing gating signals in response to said tempo pulses;

first keyswitch selector means, having a plurality of keyswitches, connected to said tone generating means for selecting one of said output tone signals and selectively passing said selected output tone signal therethrough in response to the actuation of one of said keyswitches;

second frequency dividing means for providing divisions in accordance with a second plurality of divisor numbers, said second dividing means being connected to said first keyswitch selector means for receiving said selected output tone therefrom and providing second output tone signals having a frequency relationship therebetween determined by said second divisor numbers, said relationship defining a second musical scale;

gate circuit means connected to said second frequency dividing means and to said counting means for receiving said second output tone signals and said gating signals from such tone generating means and said counting means, respectively, said gate circuit means selectively passing said second tone signals therethrough in a predetermined sequence in response to said gating signals;

second keyswitch selector means, having a plurality of second keyswitches, connected to said tone generating means for selecting one of said output tone signals and selectively passing said selected output tone signal therethrough in response to the actuation of one of said second keyswitches;

a harmonic synthesizing system including harmonic dividing means connected to said second keyswitch selector means for receiving the output tone selected thereby and having a plurality of outputs simultaneously providing harmonically related signals, a plurality of resistive attenuators each connected to one of said outputs, each of said resistive attenuators receiving one of said harmonically related signals and controlling the amplitude thereof, thereby providing a variable amplitude signal, and combining means for combining said variable amplitude signals to provide a musical tone that varies in accordance with the amplitudes of said variable amplitude signals; and

a celeste generating system including a plurality of celeste dividers connected to said second keyswitch selector means for receiving the output tone selected thereby and providing a plurality of celeste producing signals having slight frequency offsets therebetween in response to the selected tone, and means combining said celeste producing signals to provide a celeste effect.

17. An electronic musical instrument according to claim 16 further including master oscillator tuning means connected to said master oscillator for changing the frequency of said reference signal, thereby tuning said instrument.

18. An electronic musical instrument according to claim 16 further including vibrato oscillator means connected to said master oscillator for periodically changing the frequency of said reference signal thereby providing a vibrato effect.

19. An electronic musical instrument according to claim 16 wherein said frequency dividing means is a digital dividing means having said divisor numbers related to each other by a twelfth root of two ratio.

20. An electronic musical instrument according to claim 16 further including accompaniment programming means interposed between said gate circuit means and said counting means for determining said predetermined sequence.

21. An electronic musical instrument according to claim 16 further including percussion generating means connected to said counting means, said percussion generating means providing percussion signals in response to said gating signals.

22. An electronic musical instrument as described in claim 16 further including organ tone producing means coupled to said frequency dividing means for producing a plurality of organ tones in response to signals from said frequency dividing means. 

1. An electronic musical instrUment having an automatic tone accompaniment system including in combination: means for providing a plurality of musically related electrical oscillations; switch means for selecting one of said plurality of oscillations and providing selected oscillations representative thereof connected to said oscillation providing means; octave selecting means including octave dividing means having a divisor number equal to an integral multiple of two, said octave dividing means having an input connection coupled to said switch means for receiving said selected oscillations and an output connection for providing octavely related oscillations having a frequency related to the frequency of said selected oscillations by an integral multiple of two, said octave selecting means further including octave switch means having first, second and common terminals, said first terminal being coupled to said switch means and said second terminal being coupled to said octave dividing means, said switch means including means for selectively applying one of said selected and octavely related oscillations to said common terminal; accompaniment frequency dividing means for simultaneously providing a plurality of output signals having frequencies that are related to each other to form a musical scale in response to a signal applied thereto, said accompaniment frequency dividing means having an input junction and an plurality of output junctions, said input junction being connected to said common terminal for receiving the oscillations applied thereto, said accompaniment frequency dividing means including means for providing one of said plurality of output signals to each of said output junctions; tempo signal means having a plurality of outputs for providing a predetermined sequence of gating signals at each of said outputs; and gate circuit means having a plurality of input terminals, an output terminal and a plurality of control terminals, each of said input terminals being connected to one of said output junctions of said accompaniment frequency dividing means, said control terminals being connected to said outputs of said tempo signal means, said gate circuit means being responsive to said gating signals for selectively passing said output signals to said output terminal.
 2. An electronic musical instrument according to claim 1 wherein said tempo signal means includes variable rate clock means for varying the repetition rate of said gating signals to change the accompaniment tempo.
 3. An electronic musical instrument according to claim 2 further including percussion signal generating means connected to said tempo signal means for providing percussion signals in response to said gating signals.
 4. An electronic musical instrument according to claim 1 further including means for providing selective interconnections between said tempo signal means and said gate circuit means for varying the sequence of output signals passed to said output terminal connected to said outputs of said tempo signal means and said control terminals of said gate circuit means.
 5. An electronic musical instrument according to claim 4 wherein said oscillation providing means includes oscillator means and scale generating frequency dividing means connected to said oscillator means, said frequency dividing means having a plurality of divisor numbers, said divisor numbers having numeric ratios therebetween related by the twelfth root of two.
 6. An electronic musical instrument as recited in claim 5 wherein said switch means further includes a plurality of keyswitches connected to said scale generating dividing means for selecting one of said oscillations from said scale generating frequency dividing means upon actuation of one of said keyswitches to thereby select the key in which the accompaniment is played.
 7. An electronic musical instrument having a harmonic synthesizing system, said system including in combination: means for providing a plurality of musically related electrical Oscillations; switch means for selecting one of said plurality of oscillations connected to said oscillation providing means; harmonic frequency dividing means having an input and a plurality of outputs, said input being connected to said switch means and receiving said selected one of said oscillations therefrom, said harmonic dividing means including means for simultaneously providing a harmonic signal at each of said outputs, wherein each of said harmonic signals has a frequency that is harmonically related to the frequencies of the other harmonic signals and to the frequency of said oscillations; a plurality of resistive attenuators, each of said resistive attenuators being connected to one of said outputs and receiving one of said harmonically related output signals and selectively attenuating the amplitude thereof; and combining means connected to each of said resistive attenuators for receiving said harmonic signals therefrom and combining said signals to produce a musical tone having a plurality of individually adjustable harmonics.
 8. An electronic musical instrument as recited in claim 7 wherein said frequency dividing means provides variable divisor numbers for varying the frequency relationship between said harmonically related output signals.
 9. An electronic musical instrument according to claim 8 wherein said frequency dividing means includes a digital dividing circuit.
 10. An electronic musical instrument according to claim 9, said combining means further including a plurality of wave shaping filters, each of said wave shaping filters being connected to one of said resistive attenuators and receiving one of said harmonic signals and providing a wave shape modified harmonic signal.
 11. An electronic musical instrument according to claim 10 further including a second plurality of wave shaping filters switchably connected to said plurality of resistive attenuators for selectively providing a second plurality of wave shape modified harmonics.
 12. An electronic musical instrument including in combination: means for generating a plurality of musically related electrical oscillations; switch means for selecting one of said plurality of oscillations connected to said oscillation generating means; celeste generating dividing means connected to said switch means, said celeste generating means including a plurality of frequency dividers having slightly different divisor numbers connected to said switch means for receiving said selected one of said plurality of oscillations and providing a plurality of signals having celeste producing frequency offsets therebetween in response to said selected one of said plurality of oscillations; and means connected to said dividing means for combining said plurality of celeste producing signals.
 13. An electronic musical instrument as recited in claim 12 wherein said dividing means includes three parallel connected frequency dividers.
 14. An electronic musical instrument as recited in claim 12 wherein said oscillation generating means includes a scale generating divider means for producing a plurality of output signals having frequency relationships therebetween proportional to the twelfth root of two.
 15. An electronic musical instrument as recited in claim 14 wherein said switch means includes a plurality of keyswitches for selecting one of said plurality of oscillations, and wherein the divisor numbers are integral numbers that are different from each other by less than approximately three percent.
 16. An electronic musical instrument including in combination: tone generating means including a master oscillator providing a reference signal, frequency dividing means providing divisions in accordance with a plurality of divisor numbers, said dividing means being connected to said master oscillator for receiving said reference signal therefrom and providing output tone signals having a frequency relationship therebetween determined by said divisor numbers, Said relationship defining a musical scale; automatic accompaniment means including tempo clock means providing tempo pulses, counting means connected to said tempo clock means and receiving said tempo pulses therefrom, said counting means having a plurality of outputs sequentially providing gating signals in response to said tempo pulses; first keyswitch selector means, having a plurality of keyswitches, connected to said tone generating means for selecting one of said output tone signals and selectively passing said selected output tone signal therethrough in response to the actuation of one of said keyswitches; second frequency dividing means for providing divisions in accordance with a second plurality of divisor numbers, said second dividing means being connected to said first keyswitch selector means for receiving said selected output tone therefrom and providing second output tone signals having a frequency relationship therebetween determined by said second divisor numbers, said relationship defining a second musical scale; gate circuit means connected to said second frequency dividing means and to said counting means for receiving said second output tone signals and said gating signals from such tone generating means and said counting means, respectively, said gate circuit means selectively passing said second tone signals therethrough in a predetermined sequence in response to said gating signals; second keyswitch selector means, having a plurality of second keyswitches, connected to said tone generating means for selecting one of said output tone signals and selectively passing said selected output tone signal therethrough in response to the actuation of one of said second keyswitches; a harmonic synthesizing system including harmonic dividing means connected to said second keyswitch selector means for receiving the output tone selected thereby and having a plurality of outputs simultaneously providing harmonically related signals, a plurality of resistive attenuators each connected to one of said outputs, each of said resistive attenuators receiving one of said harmonically related signals and controlling the amplitude thereof, thereby providing a variable amplitude signal, and combining means for combining said variable amplitude signals to provide a musical tone that varies in accordance with the amplitudes of said variable amplitude signals; and a celeste generating system including a plurality of celeste dividers connected to said second keyswitch selector means for receiving the output tone selected thereby and providing a plurality of celeste producing signals having slight frequency offsets therebetween in response to the selected tone, and means combining said celeste producing signals to provide a celeste effect.
 17. An electronic musical instrument according to claim 16 further including master oscillator tuning means connected to said master oscillator for changing the frequency of said reference signal, thereby tuning said instrument.
 18. An electronic musical instrument according to claim 16 further including vibrato oscillator means connected to said master oscillator for periodically changing the frequency of said reference signal thereby providing a vibrato effect.
 19. An electronic musical instrument according to claim 16 wherein said frequency dividing means is a digital dividing means having said divisor numbers related to each other by a twelfth root of two ratio.
 20. An electronic musical instrument according to claim 16 further including accompaniment programming means interposed between said gate circuit means and said counting means for determining said predetermined sequence.
 21. An electronic musical instrument according to claim 16 further including percussion generating means connected to said counting means, said percussion generating means providing percussion signals in response to said gating signals.
 22. An electronic musical instrument as described in claim 16 further including organ Tone producing means coupled to said frequency dividing means for producing a plurality of organ tones in response to signals from said frequency dividing means. 